I think its density is 850kg/m^3
May i ask you what lesson this is ?
Oxygen (O), Sulphur (S) and Selenium (Se) have similar chemical properties because they all have the same number of electrons in their outermost shells.
Atoms with the same number of electrons in their outermost shells can be found in the same group.
A group consists of elements arranged in the same column (from top to bottom) on the periodic table. Elements on the same group have similar chemical properties.
Oxygen (O), Sulphur (S) and Selenium (Se) are in group eight. All three elements are highly electronegative and have 6 electrons in their outermost shell. They also carry ab charge of -2.
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Answer:
atomic number
Explanation:
The mass number of the atom (M) is equal to the sum of the number of protons and neutrons
Answer:- C) sodium has a higher ionization energy because it is smaller.
Explanations:- Ionization energy is the energy required to remove electron from valence shell of an atom in it's gaseous form.
More energy is required to remove the electron if the size of the atom is smaller as it's electrons are more strongly attracted by it's nucleus.
In periodic table, atomic size decreases on moving left to right in a period and increases on going top to bottom in a group.
Na and Cs are the elements of same group(first group) and also Cs is below Na. So, as Na is placed above Cs, the size of Na is smaller than Cs and so more energy is required to remove the electron from this smaller atom.
Hence, the right choice is C) sodium has a higher ionization energy because it is smaller.
